| China is a big country with coal,coal combustion will produce SO2,NOx,Hg and other pollutants.Also,coal consumed by coal-fired power generation accounts for 50%of coal consumption.Due to the backwardness of technology and other reasons,China's existing coal-fired units have high coal consumption and low energy utilization.With the country's increasingly stringent requirements for pollution limits in coal-fired power plants,the integration of multiple pollutant removal technologies is a hot area and mainstream trend for future research.The removal of SO2,NOx,and Hg from flue gas in coal-fired power plants is currently taken mainly by step-by-step removal.Individual equipments are operated independently and connected in series to achieve the purpose of removal.Simultaneously,the integrated technologies for desulfurization,denitrification,and mercury removal are basically in the experimental research stage,less in practical application.Low-temperature plasma technology can simultaneously oxidize a variety of pollutants in coal-fired flue gas,and activated carbon technology has also been applied in simultaneous desulfurization,denitrification,and mercury removal.This study combines low-temperature plasma technology with activated carbon technology and expand the experimental scale on the basis of small flow studies,using larger flow rates for experiments.Full-dry method is used to remove SO2,NO and Hg0 from the flue gas,a dielectric barrier discharge reactor is used to discharge O2,and the generated O3 and other O3 are injected into the mixed flue gas to oxidize SO2,NO and Hg0.Activated carbon absorbs the oxidation products and achieves simultaneous desulfurization,denitrification,and mercury removal.The results of the study show that the increase of input voltage will initially increase the O3 concentration,and the O3 concentration will decay rapidly as the discharge progresses.The greater the O2 flow rate during discharge,the lower the O3 concentration.At an input voltage of 4.0 kV and an O2 flow rate of 1000 mL/min,the O3 yield was 0.030 g/min.High-temperature flue gas also causes O3 to decompose.When the temperature reaches 220?,O3 concentration decreases from 46 g/m3 to 24 g/m3 in the first 1 min.The section of O3 oxidation explores different O3 injection amount and the oxidation efficiency of each species at different flue gas temperatures.The results show that the oxidation efficiency of SO2 is very low,and the injection of O3 increases the oxidation rate of SO2 and does not increase significantly,both being below 10%.As the amount of O3 injected increases the oxidation rate of NO,the NO2 production rate decreases.When the amount of O3 injected was 0.030 g/min at room temperature and 140?,the NO oxidation rate was 98.9%and 91.8%,and the NO2 generation rate was 18.3%and 39%,respectively.The oxidation rate of Hg0 increases with the increase of the O3 injection amount,but it is maintained at about 50%.When the amount of O3 injected into the flue gas at room temperature and 140? is 0.030 g/min,the oxidation rate of Hg0 is 59.5%and 54.8%,respectively.The O3 oxidation-active carbon adsorption section explored the effects of different types of activated carbon,adsorption methods,the amount of activated carbon,and flue gas temperature on the removal rates of SO2,NO,and Hg0.The O3 oxidation-BPL commercial activated carbon adsorption system has a very high removal efficiency for SO2.In the fluidized bed and fixed bed facilities,SO2 can reach a removal rate of more than 94.5%at room temperature and flue gas temperature of 140?.BPL commercial activated carbon has weaker NO2 adsorption capacity,which is mainly manifested as the reduction of NO2,and the removal efficiency of NO is relatively low.Biochar for corn has a strong adsorption capacity for NO2,mainly for the adsorption of NO2,and the NO concentration at the outlet is low,so the NO removal efficiency is high.Under normal temperature and 140? flue gas,the removal of NO was 95.1%and 90.5%,respectively,using a three-layer corn biochar fixed bed to adsorb after the oxidation of O3.However,the removal efficiency of SO2 by maize biochar was low.In the O3 oxidation-BPL activated carbon adsorption experiment,under the condition of normal temperature flue gas,the removal rates of NO were significantly different between the fluidized bed and the fixed bed.The removal rates of NO were 91.3%and 61.9%,respectively.There was no significant difference in the removal rate of NO at the flue gas temperature of 140 ?.In the O3 oxidation-corn biochar adsorption experiment,the SO2 adsorption effect of increasing the carbon layer height was improved,and the removal effect of NO was not significantly improved.Compared with normal temperature flue gas at 140?,the removal rates of SO2 and NO have decreased to varying degrees.The removal efficiency of Hg0 is basically stable at more than 90%.Low-temperature nitrogen adsorption analysis and surface element analysis show that BPL commercial activated carbon has a large specific surface area and a rich pore structure,but its surface oxygen-containing functional groups are less,mainly based on physical adsorption,so BPL commercial activated carbon showed excellent performance on SO2 Adsorption effect.The specific surface area and pore structure of corN biochar was much smaller than that of BPL commercial activated carbon,but the amount of oxygen-containing functional groups in the surface of the bio-char was much more,and the main manifestation was chemical adsorption.So corm biochar can achieve high NOx removal efficiency.Combining the advantages of BPL commercial activated carbon and corn biochar,the pre-BPL fluidized bed adsorption-O3 oxidation-corn biochar adsorption was designed.SO2 can reach a removal rate of over 99%,and the removal rate of NO is up to 96%,with no NO2 production.Hg0 removal rate is 93%. |
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